Airplane wing camber control

ABSTRACT

The angular configuration of a fluid control surface, with respect to the relative direction of fluid flow, is controlled by selectively heating the structural portions of only one side of the control surface to expand the structural members on the one side with respect to the structural members on the other side for warping the control surface generally from its leading to its trailing edge. Particularly, the camber of an airplane wing is changed by this selective heating for controlling the wing portion lift. Preferably, wires extend generally from the leading edge to the trailing edge of the wing as wing structural members closely adjacent the upper and lower surfaces of the wing, with both sets of wires being prestressed to provide an intermediate camber for the wing portion when the upper and lower wires are the same temperature, a generally symmetrical wing configuration when only the lower wires are heated, and a high lift maximum camber when only the upper wires are heated. The wires may be electrically heated by the passage of current therethrough, closely adjacent the wing surface for air cooling, deeply embedded in the wing structure for insulation, or contained within concentric tubes conducting a cooling or heating fluid. Further, the wires may be organic synthetic fibers with electrically conductive material embedded in them for thermal expansion, or a composite of electrically conductive and nonelectrically conductive fibers for thermal expansion, or composed of an electrostrictive material to shorten upon the passage of electrical current, or of composite structure as above mentioned, with an electrostrictive component for shortening with the passage of a current.

United States Patent Croswell, Jr.

[ May 27, 1975 AIRPLANE WING CAMBER CONTROL [75] Inventor: Thomas L.Croswell, Jr., Vienna,

Related U.S. Application Data [63] Continuation-in-part of Ser. No.201,417, Nov. 23,

1971, abandoned.

[52] U.S. Cl. 244/44; 244/134 D; 416/39 [51] Int. Cl. B64c 3/44 [58]Field of Search 244/44, 41, 42 R, 90 R,

[56] References Cited UNITED STATES PATENTS 3,042,371 7/1962 Fanti244/44 3,183,975 5/1965 Keen 416/39 Primary ExaminerTrygve M. Blix IAssistant Examiner-Barry L. Kelmachter Attorney, Agent, or FirmThomas E.Beall, Jr.

[57] ABSTRACT The angular configuration of a fluid control surface, withrespect to the relative direction of fluid flow, is controlled byselectively heating the structural portions of only one side of thecontrol surface to expand the structural members on the one side withrespect to the structural members on the other side for warping thecontrol surface generally from its leading to its trailing edge.Particularly, the camber of an airplane wing is changed by thisselective heating for controlling the wing portion lift. Preferably,wires extend generally from the leading edge to the trailing edge of thewing as wing structural members closely adjacent the upper and lowersurfaces of the wing, with both sets of wires being prestressed toprovide an intermediate camber for the wing portion when the upper andlower wires are the same temperature, a generally symmetrical wingconfiguration when only the lower wires are heated, and a high liftmaximum camber when only the upper wires are heated. The wires may beelectrically heated by the passage of current therethrough, closelyadjacent the wing surface for air cooling, deeply embedded in the wingstructure for insulation, or contained within concentric tubesconducting a cooling or heating fluid. Further, the wires may be organicsynthetic fibers with electrically conductive material embedded in themfor thermal expansion, or a composite of electrically conductive andnonelectrically conductive fibers for thermal expansion, or composed ofan electrostrictive material to shorten upon the passage of electricalcurrent, or of composite structure as above mentioned, with anelectrostrictive component for shortening with the passage of a current.

16 Claims, 8 Drawing Figures PATENTED HAY 2 7 I875 cow AIRPLANE WINGCAMBER CONTROL This application is a Continuation in part of copendingapplication, Ser. No. 201,417. now abandoned filed Nov. 23, 1971, byThomas L. Croswell, Jr., for Airplane Wing Camber Control."

BACKGROUND OF THE INVENTION There are many fluid control surfaceswherein the curvature of the fluid control surface is important for thefunction of the apparatus, for example turbine blades, turbine stators,aircraft propellers, aircraft wings for lift control, aircraftstabilizers, aircraft ailerons, and the like.

In the past, many different methods have been used to change thecurvature of aircraft wings, particularly their camber forcorrespondingly changing their lift. Usually, different wing portionshave been pivotally connected to each other and relatively moved bypiston and cylinder arrangements, or mechanical linkages. The patent toRoss US. Pat. No. 2,979,287, Apr. 11, 1961, relates to an inflatablewing with variable camber, but the surface shape is generally changedwhich is undesirable in many instances because of the increased wingthickness resulting therefrom. In the patent to Cone US. Pat. No.2,152,029, Mar. 28, 1939, upper and lower cables are used to change thecurvature of an aircraft wing, but the wing is necessarily divided intovarious sections with a connection between each section and at least oneof the cables, which presents a complexity and bulkiness that cannot betolerated in modern aircraft.

With respect to aircraft propellers, it is known to change their pitchby changing their curvature, for example with the Vischer U.S. pat. No.1,985,391, Dec. 25, 1934, which employs two pivotally connected wingportions that are relatively moved by means of a selectively heatedmember. Further, in general fan construc tion, it is known to changeblade curvature according to the environment temperature by employing abimetallic structure.

In changing the curvature of any fluid control surface, it would be mostdesirable to maintain a smooth configuration for laminar flow wheredesired. While the inflatable wing of the Ross patent provides thisdesired smooth surface and absence of any transition areas that mightproduce turbulence, the resulting thickness of the wing is generallyundesirable for high speed flight, and while the blade of the Rom patentmaintains a smooth configuration during its change without increasingits thickness, there is no selectivity since the curvature is controlledby the environment temperature.

SUMMARY OF THE INVENTION It is an object of the present invention tochange the curvature ofa fluid control surface in a smooth manner fromits leading to its trailing edge without materially changing itsthickness, and providing selective control for the curvature.

Preferably, the present invention applies to the various controlsurfaces for aircraft, for example the stabilizers, ailerons, or liftportions of the main wings. The control surface is provided withstructural wires generally extending from the leading edge to thetrailing edge on both the upper and lower surfaces, or closely adjacentthereto, so that upon selectively heating either the upper or lowerwires, they will expand to a greater extent than the unheated wires onthe opposite surface to warp or curve the surface generally over itsentire extent from its leading edge to its trailing edge. With thisstructure, it is seen that the upper and lower surfaces will at alltimes be smooth and there will be no abrupt transition portions, and thegeneral thickness of the wing may be maintained.

It is particularly desirable, with respect to changing the camber of anaircraft wing for lift control, to provide prestressed lower wires andprestressed upper wires so that normally the wing will be curved to anintermediate position for substantial lift, so that the aircraft mayland safely upon system failure. Further, this particular structurepermits heating of the lower wires to straighten out the wing andgenerally give it a symmetrical shape for high speeds, and to allowheating of only the upper wires to give it maximum curvature for landingand take-off. Preliminary computer investigations have shown that theangle between the plane of symmetry for the leading edge and the planeof symmetry for the trailing edge may vary 30 degrees with aconventionally shaped wing structure with the features of the presentinvention. While the wires or cables may be heated in any desiredmanner, for example by providing heat exchange relationship with a hotfluid, it is most preferable to resistance heat the wires by the passageof an electric current. Such electric heating will provide a very fastresponse time.

In some instances, it will be desirable to provide a slow response timefor the cooling of the wires, and this is structurally accomplished byinsulating the wires with respect to the environment fluid. A slowresponse time for the heating may be easily provided by conventionalmeans for adjusting the electric current, for example rheostats orchoppers. For a quick response cooling, the wires may be placed closelyadjacent the surface for exposure to the environment fluid or they maybe carried within cooling fluid conducting tubes. It is particularlydesirable to have a quick response time when the present invention isemployed for changing the curvature of portions of the wing that are tobe used as ailerons. With such a structure, the camber of the mainportion of the wing may be adjusted for lift purposes or the curvatureof an outer minor portion of the wing may be separately adjusted forfunctioning as an aileron, while structurally providing a smoothuninterrupted wing surface from base to tip and leading edge to trailingedge without any visible transition at any time.

Further, the wires may be organic synthetic fibers with electricallyconductive material embedded in them for thermal expansion, or acomposite of electrically conductive and non-electrically conductivefibers for thermal expansion, or composed of an electrostrictivematerial to shorten upon the passage of electrical current, or ofcomposite structure as above mentioned, with an electrostrictivecomponent for shortening with the passage of a current.

BRIEF DESCRIPTION OF THE DRAWING Further objects, features andadvantages of the present invention will become more clear from thefollowing detailed description of the drawing, wherein:

FIG. 1 is a plan view of a conventional aircraft employing the featuresof the present invention in its fixed wing structure;

FIG. 2 is a partially schematic cross sectional view taken along line 22of FIG. 1 showing the wing configuration during high speed flight;

FIG. 3 is a view similar to FIG. 2, but showing the wing configurationin its normal position for intermediate lift;

FIG. 4 is a view similar to FIG. 2, but showing the wing in its extremecurvature position for maximum lift;

FIG. 5 is a partial cross sectional view of the wing skin taken on planeperpendicular to the plane of FIG. 2', according to one construction;

FIG. 6 is a cross sectional view similar to FIG. 5, but of anotherconstruction;

FIG. 7 is a cross sectional view similar to FIG. 5, but of anotherconstruction; and

FIG. 8 is a plan view of a delta wing aircraft employing the features ofthe present invention.

DETAILED DESCRIPTION OF THE DRAWING While as set forth above, thepresent invention may be used with various types of fluid controlsurfaces, it is particularly advantageous when employed for changing thecurvature of a fluid control surface for an airplane, for example thestabilizer, the main wing section for lift purposes, or a wing portionto act as an aileron. As a specific example, the invention will be setforth below with respect to the conventionally constructed airplane ofFIG. 1 and particularly with respect to its main wing.

As shown in FIG. 1, the airplane includes a fuselage l, a cockpit 2, atail assembly 3, a stabilizer 4, a forward nose 5, and a wing 6. It isunderstood that in a conventional manner, the airplane is symmetricalwith respect to a longitudinal vertical plane, and for that reason onlyone side of the airplane has been shown in detail. In a conventionalmanner, the wing tip is elongated from its connection with the fuselage1 to its outer tip 7, and has considerable length from its leading edge8 to its trailing edge 9, with respect to the direction of relativefluid motion 10. The portion of the wing 11 closest to the fuselage hasits curvature or camber controlled according to the features of thepresent invention for changing the lift of the aircraft wing fortakeoff, landing and high speed flight. The portion 12 of the wing,adjacent the tip 7, has its curvature controlled according to thefeatures of the present invention to act as an aileron.

As shown more clearly in FIGS. 2 and 5 taken with FIG. 1, there are aplurality of structural wires 13 in the upper and lower skin of theaircraft wing for both por' tion 11 and portion 12, which wiresgenerally extend from the leading edge 8 to the trailing edge 9. Assomewhat schematically shown in FIG. 2, the upper surface 14 has astructural wire embedded in it and the lower surface 15 has a structuralwire 13 embedded in it. Preferably, the wing, as viewed in crosssection, is constructed to have a nearly symmetrical shape as shown inFIG. 2 in a cruising condition. The wires 13 in the upper surface 14 andlower surface 15 are prestressed so that the cross sectional shape ofthe wing may be controlled by the pilot. Thus, in FIG. 3, the wing willhave a slight curvature to produce sufficient lift for low speedtake-off and landing flying and relatively high speed cruise in the caseof power loss. When it is desired to fly the airplane at high speeds,the wires 13 in the lower surface 15 are heated to reduce drag. Withthis heating, the wires 13 in the lower surface 15 will expand so thatthe wing will assume the shape as shown in FIG. 2. When high lift isdesired for landing or takeoff at relatively slow speeds, the wires 13in the upper surface 14 are heated while the wires in the lower surfaceremain unheated, and accordingly only the upper wires will expand toproduce a greater curvature in the wing as shown in FIG. 4. Preliminarycomputer investigations have shown that with an otherwise conventionallyshaped and dimensioned wing, the angle between the plane of symmetry 16for the trailing edge 9 and the plane of symmetry 17 for the leadingedge 8 will be approximately 30 in the position of FIG. 4, and these twoplanes will coincide in the symmetrical position of FIG. 2. Thisdifference in camber will be sufficient for reducing the landing speedof an otherwise conventional aircraft.

The thermal expansion of the structural wires will depend upon theirthermal coefficients of expansion as to the material selected, thetemperature to which they are heated, and the other structuralcomponents of the wing. Preferably, the wing skin is constructed of theselectively heated wires 13 running from the leading edge to thetrailing edge, unheated structural wires running from the fuselage tothe tip 7, and a skin resin. Also, structural wires 23 may run from thefuselage to the tip 7 in a top set and a lower set generallyperpendicular to the wires 13 and independently heated in sets forcontrolling wing twist and/or dihedral and/or sweepback. With thetemperature employed, the wires may have an expansion of 1.5 percentbetween their cold state and heated state. Preferably, the wing would beof a hollow construction with the above-mentioned upper skin and lowerskin separated by a honeycomb or foam structure or other flexiblemembranes.

While any type of heating may be employed, it is most desirable andconvenient to provide electric resistance heating for the wires 13.Accordingly, the wires are connected at their trailing edge 9 to theground for the electrical system and separately connected at theirleading edge 8 to a controlled source of current. That is, all or groupsof the upper wires 13 may be selectively connected to a source ofcurrent and all or groups of the lower wires may be selectivelyconnected to a source of current independently of the upper wires. Thewires or groups of wires are heated by thus passing either direct oralternating current therethrough from the leading to the trailing edge.

For a fairly quick response with respect to cooling the wires, which isparticularly desirable with respect to the group 12 functioning as anaileron, it is desirable to have the wires closely adjacent the exposedsurface of the skin. Such a structure is shown in FIG. 5. The wires 13are embedded in a layer of resin 18 that may in fact be resin mixed withfibers, or a laminated structure. The coefficient of thermal expansionfor the resin may be chosen to correspond to or in some other waydesirably complement the coefficient of expansion for the wires 13.After the wires 13 in FIG. 5 have been heated by the passage of currenttherethrough. they are rapidly cooled by air flowing over the exposedsurface 19 after the current is shut off or reduced. The oppositesurface 20 of the skin is suitably laminated to a honeycomb or foam coreor flexible membranes (not shown).

The skin structure of FIG. 6 may be employed when it is desired tothermally insulate the wires, heat the wires by the passage ofa heatexchange fluid, or rapidly cool the wires by the passage of a heatexchange fluid.

The structure of FIG. 6 is particularly desirable for the aileronportion 12 of the wing in that the thermal response for the wires may bemade very rapid. As before, the skin is constructed of a resin 21, butwith FIG. 6 a plurality of tubes 22 surround the wires 13 in spacedrelationship. Thus, there is produced an annular passage between thewires I3 and their tubes 22, for the reception of a heat exchange fluidto either heat or cool the wires. Most desirably, the wires are heatedas before by the passage of electricity and are cooled by the passage ofa cooling fluid to provide the rapid response for aileron control.

In some instances, it is desirable to have a slow cooling and a slowheating for the wires being controlled, particularly with respect to thelift portion 11 of the wing. Thus, there will be no rapid changes inlift which might produce instability in the plane. It is a quite simplematter to control the speed of heating for the wires by merelycontrolling the increase in current being fed to the wires by means of arheostat or chopper. The cooling may be controlled by theabove-mentioned cooling fluid in FIG. 6 exactly over a wide range, fixedfor rapid cooling as in FIG. 5, or fixed for slow cooling as in FIG. 7.

As shown in FIG. 7, the skin is constructed of a resin 23, of a type asset forth above, for deeply embedding the wires 13. The resin 23 may bechosen for its heat insulating properties to provide any desiredcooling. Preferably, the skin is of a laminated construction with anouter layer 24 chosen for its durability and strength without regard toits insulating properties.

The above features as set forth specifically with respect to FIGS. 2through 7 may be equally well employed with the wing of a delta wingtype aircraft as shown in FIG. 8, with the construction of FIG, 2 existing with respect to the section line 22 of FIG. 8. Accordingly, all ofthe preceding discussion applies equally well to FIG. 8.

Further, the features as set forth with respect to FIGS. 2-7 may beapplied with respect to the construction of a blade or stator for acompressor or turbine to change the output of the rotatable machine.However, the features of the present invention are particularlydesirable when employed for controlling the lift or aileron surfaces ofan aircraft wing.

It is contemplated that various types of electrically conductiveresistance wires may be used for thermal expansion in the abovedisclosure, which wires may take the following forms: an electricallyconductive metallic element or non-meteallic element sheaved orintegrally bonded to a non-electrically conductive outer tube that wouldbe heated and thermally expand; a twisted, braided, interwoven or otherfilament or fiberlike materials wherein some are electrically conductivefor resistance heating and others are nonelectrically conductive forthermal expansion by heat transfer from the electrically conductiveones; a material composed of a normally non-conductive material withconductive material as a filler so that the composite article iselectrically conductive; a composite material comprising a plurality oflayers of sheet material wherein some are electrically conductive andothers are not electrically conductive. In the above cases, theelectrically conductive material would act as the resistance element forheating purposes and thermally expand as a structural member, andfurther transfer heat to the adjacent non-electrically conductivematerial that would also thermally expand as a structural member. Someof the non-conductive materials may be, for example, organic fibers, forexample a commercially available material from DuPont Chemical Companycalled PRD-49 or the commercially available material Nomex, which lattermaterial is a high temperature nylon.

Further, it has been found that various composite materials willrestrict or contract when subjected to an electrical current, forexample it has been found that intermixed electrically conductivegraphite particles or fibers and non-conductive, for example organic,particles or fibers when subjected to an electrical current willconstrict. It is thought that with graphite fibers providing resistanceheating, epoxy between such fibers will by heat transfer thermallyexpand and pull the fibers apart to thereby shorten the graphite fibers,even though the graphite fibers themselves are not electrostrictive innature. This is only a theory, but it is a fact that such compositematerials, particularly graphite fibers embedded in epoxy resin, have areduction in length with the application of an electric current throughthe graphite fibers. Further, the graphite fibers, in addition to theadvantage of being light in weight, have a tensile strength that is manytimes that of steel.

Further, graphite fibers, as mentioned above, may be used as theelectrically conductive material in the previously mentioned compositewire constructions. Graphite fibers may at the present time becommercially obtained from Hercules Powder Company.

Further, the structural elements that will expand or contract to producecurvature of the aerodynamic surface according to the foregoingembodiments may be constructed of electrostrictive material, that is amaterial that will exhibit a mechanical stress tending to producedeflection, expansion or contraction when subjected to electricalstress, which material may or may not be crystalline. If the materialwill exhibit expansion upon being electrically stressed, it may bedirectly substituted for the previously mentioned materials that willthermally expand with electrical resistance heating, with such materialspreferably being prestressed so that they will relax upon expansion andproduce the curvature. Further, when the electrostrictive materialcontracts upon being electrically stressed, it may be prestressed or notwhen applied as a structural member of the aerodynamic surface, and itsconstriction will accordingly warp the surface in the precedingembodiments.

While crystalline barium titanate ceramic is a well knownelectrostrictive material, there are many other electrostrictivematerials that would be particularly adapted for use in the presentsituation. Particularly, polycrystalline lead zirconate titanate ceramicis an electrostrictive material having suitable properties forapplication to the present invention, because it has the property ofexpanding and contracting in length when a voltage is applied in thedirection of polarization. A positive portion of a square wave drivepulse will engergize this specific material so that it will expand,while the negative portion of a square wave drive pulse will cause thematerial to contract. Therefore, a square wave drive pulse may be usedso that its positive portion or only its negative portion may beselectively applied to the electrostrictive material for selectiveexpansion or contraction. Such material could be used as a non-stressedstructural element with contraction causing warping, or it could be usedas a prestressed structural element so that with a positive voltage itsexpansion would cause warping in one direction and with negativevoltage, its restriction would cause warping in the opposite direction.This latter specific material with the application of 30-50 volts per0.00l inch of thickness will have a total displacement of approximately0.001 inch per inch of length.

In the above variation of the present invention that employs anelectrostrictive material, such electrostrictive material may bereplaced by a magnetostrictive material, which is defined as a materialhaving the property of changing in physical size or shape under theinfluence of a magnetic field. There are many known types of suchmagnetostrictive materials, which may be employed in the presentinvention as structural members having adjacent means for producing avariable magnetic field, for example a specific form may be amagnetostrictive sheet laminated with a printed circuit forming coils toproduce a magnetic field varying according to the electrical drivevariation. Such structural magnetostrictive material would contract orexpand selectively to correspondingly warp the aerodynamic surface inone or the other direction, and prestressing may or may not be applied.

While the most preferred forms of the present invention have been setforth in detail above and these details are highly desirable in theirown right, further variations, modifications and embodiments arecontemplated according to the broader aspects of the present inventionas defined by the spirit and scope of the following claims.

What is claimed is:

I. An airplane, comprising: a fuselage; a fluid flow affecting generallyplanar member extending from said fuselage and having opposedaerodynamic surfaces defining generally a leading edge and a trailingedge; a first set of generally parallel structural pretensioned wiresclosely adjacent one of said aerodynamic surfaces and a second set ofstructural pretensioned wires that is in structural opposition to saidfirst set; and means for selectively heating only said first set ofstructural pretensioned wires for thermally expanding said first set ofstructural pretensioned wires to a substantial extent to warp saidplanar member in one direction and substantially affect its aerodynamiccharacteristics for the inflight control of the airplane.

2. The airplane of claim 1, including means for separately heating onlysaid second set of structural pretensioned wires without heating saidfirst set of structural pretensioned wires to thermally expand saidsecond set of structural pretensioned wires and warp the planar memberin the opposite direction from said one direction.

3. The airplane of claim 2, wherein one of said sets of structuralpretensioned wires is normally pretensioned in its unheated state to agreater extent than the other of said set of structural pretensionedwires.

4. The airplane of claim 2, wherein said planar member is a wing of theaircraft; including a third set of generally parallel structuralpretensioned wires closely adjacent the one of said aerodynamic surfacesand being generally perpendicular to the wires of said first set, afourth set of generally parallel structural pretensioned wires closelyadjacent the other of said aerodynamic surfaces and being generallyperpendicular to the wires first sets of wires extend generally from therespective leading edge to the respective trailing edge for a majorportion of its associated wing to control the wing camber and thuscontrol the airplane lift; each of said wings having a separate set ofgenerally parallel structural pretensioned wires closely adjacent atleast one of their aerodynamic surfaces outwardly from said first set;and means for selectively and independently heating said separate setsof structural pretensioned wires to warp their associated wing portionsto function as ailerons.

6. The airplane of claim 1, wherein said planar member has outercontinuous resinous skins forming said aerodynamic surfaces; and saidwires are embedded within their respective one of said resinous skinsfor a major portion of the extent of said one aerodynamic surface.

7. A fluid flow controlling member having opposed fluid contactingsurfaces defining a leading edge and a trailing edge with respect to therelative fluid flow; a plurality of generally parallel pretensionedwires generally extending in the direction from said leading edge tosaid trailing edge closely adjacent at least one of said surfaces andsaid pretensioned wires maintain said surfaces in a predetermined shape;and means selectively heating only the wires in said one surface forthermally expanding said pretensioned wires to expand said member in thedirection of fluid flow on the side having said one surface to a greaterextent than the other side having the other surface to generally warpsaid member from its leading edge to its trailing edge in a smoothmanner.

8. The control member of claim 7, wherein said pretensioned wires areelectrically conductive wires generally insulated from each other andsaid means for heating includes means for passing electric currentthrough said wires.

9. The device of claim 8, including a second set of generally parallelpretensioned wires closely adjacent the other of said surfaces andelectrically insulated from said first mentioned pretensioned wires atone of their ends; said means for heating including means for supplyingan electric current to the second set of pretensioned wiresindependently of said first mentioned pretensioned wires in one mode ofoperation and supplying an electric current to the first mentionedpretensioned wires independently of said second set of pretensionedwires in another mode of operation.

10. The device of claim 7, including a separate tubular membersurrounding each of said pretensioned wires for substantially its entireextent; and means for passing a heat exchange fluid through said tubesin contact with said pretensioned wires.

11. The device of claim 7, wherein said pretensioned wires extend forsubstantially the full extent of said controlling member in thedirection of fluid flow from its leading edge continuously to itstrailing edge.

12. A method for controlling the curvature of a fluid flow controlmember having a leading edge generally transverse to the fluid flow, atrailing edge generally transverse to the fluid flow, opposed surfacesover which the fluid flows, and opposed structural generally parallelwires extending in the direction of fluid flow and respectively adjacenteach surface. comprising: selectively heating only the structural wiresadjacent one surface for a portion of said member to expand the heatedstructural wires on the one side to at least an extent greater than thestructural wires adjacent the other surface to curve the member in crosssection generally from said leading edge to said trailing edge.

13. The method of claim 12, including the step of at other timesselectively heating only the structural wires adjacent said othersurface to expand the other strutural wires on the other side andreversely curve said member in cross section generally from said leadingedge to said trailing edge, with the member assuming a curvature midwaybetween the curvatures provided by said first two steps when thestructural wires are not 10 heated.

14. The method of claim 13, wherein each of said steps of heating heatthe structural wires sufficiently to change the angle between the planeof symmetry for the leading edge and the plane of symmetry for thetrailing edge for the portion being selectively heated more than 5between the first step and the second step.

15. The method of claim 12, wherein said elongated member is the wing ofan aircraft; and said step of selective heating is carried out duringflight of the aircraft to vary the camber of the wing andcorrespondingly change the lift for the airplane.

16. The method of claim 12, wherein said step of heating includespassing an electrical current through the structural wires to be heated.

1. An airplane, comprising: a fuselage; a fluid flow affecting generallyplanar member extending from said fuselage and having opposedaerodynamic surfaces defining generally a leading edge and a trailingedge; a first set of generally parallel structural pretensioned wiresclosely adjacent one of said aerodynamic surfaces and a second set ofstructural pretensioned wires that is in structural opposition to saidfirst set; and means for selectively heating only said first set ofstructural pretensioned wires for thermally expanding said first set ofstructural pretensioned wires to a substantial extent to warp saidplanar member in one direction and substantially affect its aerodynamiccharacteristics for the inflight control of the airplane.
 2. Theairplane of claim 1, including means for separately heating only saidsecond set of structural pretensioned wires without heating said firstset of structural pretensioned wires to thermally expand said second setof structural pretensioned wires and warp the planar member in theopposite direction from said one direction.
 3. The airplane of claim 2,wherein one of said sets of structural pretensioned wires is normallypretensioned in its unheated state to a greater extent than the other ofsaid set of structural pretensioned wires.
 4. The airplane of claim 2,wherein said planar member is a wing of the aircraft; including a thirdset of generally parallel structural pretensioned wires closely adjacentthe one of said aerodynamic surfaces and being generally perpendicularto the wires of said first set, a fourth set of generally parallelstructural pretensioned wires closely adjacent the other of saidaerodynamic surfaces and being generally perpendicular to the wires ofsaid second set, and means for separately heating said third and fourthsets for selective control of surface contour perpendicular to thecontrol of said first and second sets of wires; and including a secondopposed aircraft wing a mirror image of said first mentioned wing. 5.The airplane of claim 4, wherein each of said wing first sets of wiresextend generally from the respective leading edge to the respectivetrailing edge for a major portion of its associated wing to control thewing camber and thus control the airplane lift; each of said wingshaving a separate set of generally parallel structural pretensionedwires closely adjacent at least one of their aerodynamic surfacesoutwardly from said first set; and means for selectively andindependently heating said separate sets of structural pretensionedwires to warp their associated wing portions to function as ailerons. 6.The airplane of claim 1, wherein said planar member has outer continuousresinous skins forming said aerodynamic surfaces; and said wires areembedded within their respective one of said resinous skins for a majorportion of the extent of said one aerodynamic surface.
 7. A fluid flowcontrolling member having opposed fluid contacting surfaces defining aleading edge and a trailing edge with respect to the relative fluidflow; a plurality of generally parallel pretensioned wires generallyextending in the direction from said leading edge to said trailing edgeclosely adjacent at least one of said surfaces and said pretensionedwires maintain said surfAces in a predetermined shape; and meansselectively heating only the wires in said one surface for thermallyexpanding said pretensioned wires to expand said member in the directionof fluid flow on the side having said one surface to a greater extentthan the other side having the other surface to generally warp saidmember from its leading edge to its trailing edge in a smooth manner. 8.The control member of claim 7, wherein said pretensioned wires areelectrically conductive wires generally insulated from each other andsaid means for heating includes means for passing electric currentthrough said wires.
 9. The device of claim 8, including a second set ofgenerally parallel pretensioned wires closely adjacent the other of saidsurfaces and electrically insulated from said first mentionedpretensioned wires at one of their ends; said means for heatingincluding means for supplying an electric current to the second set ofpretensioned wires independently of said first mentioned pretensionedwires in one mode of operation and supplying an electric current to thefirst mentioned pretensioned wires independently of said second set ofpretensioned wires in another mode of operation.
 10. The device of claim7, including a separate tubular member surrounding each of saidpretensioned wires for substantially its entire extent; and means forpassing a heat exchange fluid through said tubes in contact with saidpretensioned wires.
 11. The device of claim 7, wherein said pretensionedwires extend for substantially the full extent of said controllingmember in the direction of fluid flow from its leading edge continuouslyto its trailing edge.
 12. A method for controlling the curvature of afluid flow control member having a leading edge generally transverse tothe fluid flow, a trailing edge generally transverse to the fluid flow,opposed surfaces over which the fluid flows, and opposed structuralgenerally parallel wires extending in the direction of fluid flow andrespectively adjacent each surface, comprising: selectively heating onlythe structural wires adjacent one surface for a portion of said memberto expand the heated structural wires on the one side to at least anextent greater than the structural wires adjacent the other surface tocurve the member in cross section generally from said leading edge tosaid trailing edge.
 13. The method of claim 12, including the step of atother times selectively heating only the structural wires adjacent saidother surface to expand the other strutural wires on the other side andreversely curve said member in cross section generally from said leadingedge to said trailing edge, with the member assuming a curvature midwaybetween the curvatures provided by said first two steps when thestructural wires are not heated.
 14. The method of claim 13, whereineach of said steps of heating heat the structural wires sufficiently tochange the angle between the plane of symmetry for the leading edge andthe plane of symmetry for the trailing edge for the portion beingselectively heated more than 5* between the first step and the secondstep.
 15. The method of claim 12, wherein said elongated member is thewing of an aircraft; and said step of selective heating is carried outduring flight of the aircraft to vary the camber of the wing andcorrespondingly change the lift for the airplane.
 16. The method ofclaim 12, wherein said step of heating includes passing an electricalcurrent through the structural wires to be heated.